diff --git a/packages/components/src/modal/README.md b/packages/components/src/modal/README.md
index e6ff2a57698046..6420d07ee15b88 100644
--- a/packages/components/src/modal/README.md
+++ b/packages/components/src/modal/README.md
@@ -223,7 +223,7 @@ This property when set to `true` will render a full screen modal.
 
 #### `size`: `'small' | 'medium' | 'large' | 'fill'`
 
-If this property is added it will cause the modal to render at a preset width, or expand to fill the screen.
+If this property is added it will cause the modal to render at a preset width, or expand to fill the screen. This prop will be ignored if `isFullScreen` is set to `true`.
 
 -   Required: No
 
diff --git a/packages/components/src/modal/types.ts b/packages/components/src/modal/types.ts
index 7b5dcd2a38ff6b..0a422718b1be14 100644
--- a/packages/components/src/modal/types.ts
+++ b/packages/components/src/modal/types.ts
@@ -98,7 +98,8 @@ export type ModalProps = {
 	isFullScreen?: boolean;
 	/**
 	 * If this property is added it will cause the modal to render at a preset
-	 * width, or expand to fill the screen.
+	 * width, or expand to fill the screen. This prop will be ignored if
+	 * `isFullScreen` is set to `true`.
 	 *
 	 * Note: `Modal`'s width can also be controlled by adjusting the width of the
 	 * modal's contents, or via CSS using the `style` prop.